: 1) select 50 unique days from a year; 2) means everyone has 365 choices.Continuous variables can be processed using length or area.
union == or, intersection == and; 并集和交集分别相当于逻辑符号 || 和 &&
1 Random Events and Probability
1.2 Basics of Probability
1.3 Conditional Probability
1.4 Independence of Random Events
2 Random Variables and Distributions
2.1 Random Variables